Effects of Y doping ions on microstructure, dielectric response, and electrical properties of Ca_1−3x/2Y _x Cu₃Ti₄O₁₂ ceramics

The effects of Y³⁺ doping ions on ceramic microstructure, dielectric response, and electrical properties of Ca_1−3x/2Y _x Cu₃Ti₄O₁₂ (x = 0, 0.05, 0.10, and 0.15) ceramics prepared by a modified sol–gel method were investigated. A grain size of Ca_1−3x/2Y _x Cu₃Ti₄O₁₂ was reduced by Y³⁺ ions due to a solute drag effect. Substitution of CaCu₃Ti₄O₁₂ ceramics with suitable Y³⁺ concentration of 5 at. % can improve dielectric properties with high-dielectric permittivity of ε′ ~ 1.37 × 10⁴ and low tanδ ~ 0.05 at 1 kHz. The results revealed that the relationship of the mean grain size and ε′ cannot be formulated. Using impedance spectroscopy analysis, the grain boundary resistance (R _gb) of Ca_1−3x/2Y _x Cu₃Ti₄O₁₂ ceramics was found to be strongly enhanced by Y³⁺ doping ions with x = 0.05. With further increasing x from 0.05 to 0.15, R _gb decreased. While the grain resistance tended to increase with increasing Y³⁺ concentration (x = 0–0.15). Variation of a low-frequency tanδ value in all Ca_1−3x/2Y _x Cu₃Ti₄O₁₂ ceramics due to the influence of Y³⁺ substitution was well consistent with their changes in R _gb values. Non-Ohmic properties of Ca_1−3x/2Y _x Cu₃Ti₄O₁₂ ceramics were also investigated.